Cu₂(ZnSn)(SSe)₄ (CTZSS) has an important advantages over CuInGaSe₂ (CIGS) as photovoltaic thin film due to its high band gap. Generating such thin film materials by electrochemical methods is particularly attractive because of its high throughput and low cost^1-3. Numerous publications reports CTZS electroplating; however, the electroplating process still has a serious challenges such as a sulfur atomic ration and the annealing process due to low partial pressure⁴.

We present in this work a new electrolyte composition which allows the direct electroplating of CTZSS from a single bath. The electrolyte is significantly more dilute in comparison to common electrolytes designated in the literature^1-4. The bath composition we introduce is: 0.0031 M CuSO₄, 0.0023 M ZnSO₄, 0.026 M SnCl₂, 0.004 M Na₂S₂O₃, 0.026 M H₂SeO₃ and 0.11 mM Na₂S₂O₃. PHydrion is used to buffer the electrolyte to pH=2, and 0.76 M LiCl is used as supporting electrolyte.

Electrodeposition experiments was carried at a rotating disk electrode which provides quantitative characterization of the flow (ambient temperature). Comprehensive electrochemical behavior study at different electrode rotation rates are provided in Fig. 1. The effects of flow speed on the CTZSS alloy atomic composition and its adhesion to the back contact are discussed. The post treatment annealing was conducted under sulfur element atmosphere with no need for material addition at this step. The amount of sulfur and selenium was optimized. The final composition was investigated using Energy-dispersive X-ray spectroscopy technique (EDS) Fig. 2. XRD technique used to analyze CTZS crystallography and thickness.

Acknowledgements

Case Western Reserve University for using their instruments

References

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